Aspergillus nidulans

Macroscopic morphology

Colonies on potato dextrose agar at 25°C are dark green with orange to yellow in areas of cleistothecial production. Reverse is purplish to olive. Exudate is usually present and may be brown to purplish. Growth rate is slow to moderate in comparison with other clinically significant Aspergillus species.

Microscopic morphology

Hyphae are septate and hyaline. Conidial heads are columnar. Conidiophores are brown, short (60-150 µm in length), and smooth-walled. Vesicles are hemispherical, small (8-12 µm in diameter), with metulae and phialides occurring on the upper portion. Conidia are globose (3-4 µm) and rough. A. nidulans is a homothallic species capable of producing the teleomorph (sexual stage) without mating studies. The ascomycetous telemorph (Emericella nidulans) produces brown to black globose cleistothecia (100-250 µm) that are engulfed with globose Hülle cells. Ascospores are reddish brown, lenticular (4 x 5 µm), with two longitudinal crests[531, 1215, 1875, 2202].

Special notes

This species is the etiologic agent of cutaneous aspergillosis [1386], maxillary sinus disease[1066], [1547], osteomyelitis [609], pulmonary disease[1552], [1969], guttural pouch mycosis in a horse[356], [931], and a cerebral abscess[1578]. Resistance to itraconazole being conferred by extra copies of the A-nidulans P-450 14 alpha-demethylase gene, pdmA, has been reported [1698], as well as reports of amphotericin B resistance[1229].